Uterine fibroids are well-defined, non-cancerous tumors that are commonly found in the smooth muscle layer of the uterus. In many instances, uterine fibroids can grow to be several centimeters in diameter and may cause symptoms like menorrhagia (prolonged or heavy menstrual bleeding), pelvic pressure or pain, and reproductive dysfunction. Current treatments for uterine fibroids include hysteroscopic resection, which involves inserting a hysteroscope (i.e., an imaging scope) into the uterus transcervically (i.e., through the vagina), and then cutting away the fibroid from the uterus using a tissue removal device delivered to the fibroid via a channel in the hysteroscope.
Hysteroscopic resection procedures typically fall into one of two categories. In one category, an electrocautery device in the form of a loop-shaped cutting wire is fixedly mounted on the distal end of the hysteroscope, the combination of a hysteroscope and electrocautery device is referred to as a “resectoscope.” Examples of resectoscope devices are disclosed, for example, in U.S. Pat. No. 5,906,615, issued May 25, 1999, which is fully incorporated herein by reference. In the other category of hysteroscopic resection procedures, an electromechanical cutter is inserted through a working channel of the hysteroscope. Tissue is then removed by contacting the end of the cutter, which typically has a rotating cutting element, with the targeted tissue attached to the uterus wall. Examples of hysteroscopic resection procedures employing an electromechanical cutter are disclosed, for example, in U.S. Pat. No. 9,095,366, issued Aug. 4, 2015, which is fully incorporated herein by reference.
In both of the above-described categories of hysteroscopic resection procedures, prior to fibroid removal, the uterus is typically distended to create a working space within the uterus. Such a working space does not normally exist in the uterus because the uterus is a flaccid organ. As such, the walls of the uterus are typically in contact with one another when in a relaxed state. The conventional technique for creating such a working space within the uterus is to administer a fluid to the uterus through the hysteroscope under sufficient pressure to cause the uterus to become distended.
By way of illustration, in the tissue removal system illustrated in FIG. 1(b) of U.S. Pat. No. 8,568,424, hereby incorporated herein by reference, distending fluid is delivered to the patient's uterus through a hysteroscope. The distending fluid is removed from the patient through three separate pathways. In particular, the distending fluid is removed from the patient (e.g., during distention and rinsing), through a removable outflow channel during a diagnostic hysteroscopy or passage of the tissue removal device, with additional fluid being lost through cervical leakage. The distending fluid that leaks through the cervix is captured in a drape and pumped to a collection container in order to account for same. The removable outflow channel is not shown in FIG. 1(b), but is described in column 16, lines 41-50 of U.S. Pat. No. 8,568,424.
Examples of the fluid used conventionally to distend the uterus include gases like carbon dioxide or, more commonly, liquids like water or certain aqueous solutions, e.g., a saline or other physiologic solution or a sugar-based or other non-physiologic solution. Because the distending fluid is administered under pressure, which may be as great as 100 mm Hg or greater, there is a risk, especially when vascular tissue is cut, that the distending fluid may be taken up by blood vessel(s) in the uterus, referred to as “intravasation,” which may be harmful to the patient if too much of the distension fluid is taken up. Thus, during a procedure involving fluid distension of the uterus, it is customary to monitor the fluid uptake on a continuous basis using a scale system. Despite the risks of intravasation, with proper monitoring of fluid uptake, hysteroscopic resection is a highly effective and simple technique for removing uterine fibroids.